The U.S. response could involve military, political and economic actions, and the military options could range from no action at all to airstrikes or less visible moves such as cyberattacks. One likely move would be for the U.S. to provide additional military support to help Saudi Arabia defend itself from attacks from the north, since most of its defenses have focused on threats from Houthis in Yemen to the south…

U.S. officials were unwilling to predict what kind of response Trump will choose. In June, after Iran shot down an American surveillance drone, Trump initially endorsed a retaliatory military strike then abruptly called it off because he said it would have killed dozens of Iranians. The decision underscores the president’s long-held reluctance to embroil the country in another war in the Middle East.

Instead, Trump opted to have U.S. military cyber forces carry out a strike against military computer systems used by Iran’s Revolutionary Guard to control rocket and missile launchers, according to U.S. officials.

The Pentagon said the U.S. military is working with Saudi Arabia to find ways to provide more protection for the northern part of the country.